Remote controls, for everything from televisions to vehicle alarm systems to ceiling fans, have become ubiquitous. The remote control systems allow an operator to control the functions of a variety of devices from a remote position. While the primary benefit of remote control systems is convenience, the systems also provide increased safety and functionality. For example, many automobiles are equipped with remote locking and unlocking systems and/or remote activated alarm systems. In these systems, a small remote control, often called a key fob, with one or more buttons, is operable to control locking and unlocking of the vehicle doors and/or arming and disarming of the alarm system. Remote unlocking of the vehicle doors is certainly more convenient than using a traditional key to unlock the doors. However, the system also provides safety benefits. A person walking alone at night may push “unlock” on the remote to unlock the car door as they approach the car. This significantly reduces the amount of time required to enter the car and reduces the time during which the person is exposed to potential risk. Also, in many vehicles, remote locking or unlocking causes other functions to be activated. For example, many vehicles illuminate interior lighting when the vehicle is remotely unlocked. This allows the owner to easily see whether the car has been tampered with and also helps in locating the vehicle. Some vehicles illuminate exterior lighting or sound a signal, such as the vehicle horn, during either locking or unlocking. These functions serve several purposes. First, the visual or audio signal helps the user to locate their vehicle. Additionally, the light or sound may serve to scare away undesirable characters who may be near the vehicle. Finally, the audible or visual signal helps to confirm that the signal from the remote control has been received by the vehicle.
A shortcoming of current remote control systems is that the systems are incapable of adjusting their function based on the distance between the remote control and the receiver. Remote control unlocking and locking systems for vehicles serve as an excellent example of why this shortcoming is undesirable. In vehicles which provide an audible alert when the vehicle has been locked or unlocked, the audible alert is of a constant volume level. Automakers attempt to choose a sound and volume level which serves to alert the user to the functioning of the remote control under a variety of conditions. However, this nonadjustable level is always a compromise. In a noisy environment, such as along a city street, the standard volume level of an audible signal associated with locking or unlocking may be insufficient to overpower the background sound. Also, if the user is far from the vehicle when using the remote, the audible signal may be insufficient to reach them at this distance. This is especially a problem in that the effectiveness of the remote control drops as the distance increases. When the user is far from the vehicle, it is more important to receive a confirmation that the signal has been received so that the user does not repeatedly activate the remote control. At the opposite end of the spectrum, preset audible signals are often too loud in some settings. A user who parks in a small enclosed parking area, such as a parking garage, or in a quiet residential area, may find that the audible alert associated with remote locking of their vehicle is embarrassingly loud. In light of the above, there is a need for remote control systems that adjust their function in response to distance between the remote control and the receiver.